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Stuart N Vogel - One of the best experts on this subject based on the ideXlab platform.
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spatially extended and high velocity Dispersion molecular Component in spiral galaxies single dish versus interferometric observations
The Astronomical Journal, 2015Co-Authors: Anahi Calduprimo, Andreas Schruba, Fabian Walter, Adam K Leroy, Alberto D Bolatto, Stuart N VogelAbstract:Recent studies of the molecular medium in nearby galaxies have provided mounting evidence that the molecular gas can exist in two phases: one that is clumpy and organized as molecular clouds and another one that is more diffuse. This last Component has a higher velocity Dispersion than the clumpy one. In order to investigate these two molecular Components further, we compare the fluxes and line widths of CO in NGC 4736 and NGC 5055, two nearby spiral galaxies for which high-quality interferometric as well as single-dish data sets are available. Our analysis leads to two main results: (1) employing three different methods, we determine the flux recovery of the interferometer as compared to the single-dish to be within a range of 35%–74% for NGC 4736 and 81%–92% for NGC 5055, and (2) when focusing on high (S/N ≥ 5) lines of sight (LOSs), the single-dish line widths are larger by ∼(40 ± 20)% than the ones derived from interferometric data, which is in agreement with stacking all LOSs. These results point to a molecular gas Component that is distributed over spatial scales larger than 30″(∼1 kpc), and is therefore filtered out by the interferometer. The available observations do not allowmore » us to distinguish between a truly diffuse gas morphology and a uniform distribution of small clouds that are separated by less than the synthesized beam size (∼3″ or ∼100 pc), as they would both be invisible for the interferometer. This high velocity Dispersion Component has a Dispersion similar to what is found in the atomic medium, as traced through observations of the H i line.« less
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spatially extended and high velocity Dispersion molecular Component in spiral galaxies single dish vs interferometric observations
arXiv: Astrophysics of Galaxies, 2015Co-Authors: Anahi Calduprimo, Andreas Schruba, Fabian Walter, Adam K Leroy, Alberto D Bolatto, Stuart N VogelAbstract:Recent studies of the molecular medium in nearby galaxies have provided mounting evidence that the molecular gas can exist in two phases: one that is clumpy and organized as molecular clouds and another one that is more diffuse. This last Component has a higher velocity Dispersion than the clumpy one. In order to investigate these two molecular Components further, we compare the fluxes and line widths of CO in NGC 4736 and NGC 5055, two nearby spiral galaxies for which high-quality interferometric as well as single-dish data sets are available. Our analysis leads to two main results: 1) Employing three different methods, we determine the flux recovery of the interferometer as compared to the single-dish to be within a range of 35-74% for NGC4736 and 81-92% for NGC5055, and 2) when focusing on high (SNR>5) lines of sight, the single-dish line widths are larger by ~(40+-20)% than the ones derived from interferometric data; which is in agreement with stacking all lines of sight. These results point to a molecular gas Component that is distributed over spatial scales larger than 30"(~1kpc), and is therefore filtered out by the interferometer. The available observations do not allow us to distinguish between a truly diffuse gas morphology and a uniform distribution of small clouds that are separated by less than the synthesized beam size (~3" or ~100pc), as they would both be invisible for the interferometer. This high velocity Dispersion Component has a Dispersion similar to what is found in the atomic medium, as traced through observations of the HI line.
Kostyantyn Slyusarenko - One of the best experts on this subject based on the ideXlab platform.
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magnetic field control of the ordering of two Component suspension of hard rods
Philosophical Transactions of the Royal Society A, 2013Co-Authors: Kostyantyn Slyusarenko, Victor Yu Reshetnyak, Yu ReznikovAbstract:The Onsager theory of hard rod Dispersion in a neutral solvent is extended to a case of two-Component Dispersion consisting of both non-magnetic and magnetic rods. It was found that the alignment of magneto-sensitive Dispersion Component by a magnetic field leads to the alignment of non-magnetic Component in the Dispersion and to an elimination of the isotropic phase. This effect is significant even at low relative concentrations of magnetic rods and leads to a magnetically induced anisotropy in a non-magnetic Dispersion of rods mixed with the magnetic ones.
Giovanni Bistoni - One of the best experts on this subject based on the ideXlab platform.
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effect of electron correlation on intermolecular interactions a pair natural orbitals coupled cluster based local energy decomposition study
Journal of Chemical Theory and Computation, 2019Co-Authors: Ahmet Altun, Frank Neese, Giovanni BistoniAbstract:The development of post-Hartree–Fock (post-HF) energy decomposition schemes that are able to decompose the HF and correlation Components of the interaction energy into chemically meaningful contributions is a very active field of research. One of the challenges is to provide a clear-cut quantification to the elusive London Dispersion Component of the intermolecular interaction. London Dispersion is well-known to be a pure correlation effect, and as such it is not properly described by mean field theories. In this context, we have recently developed the local energy decomposition (LED) analysis, which provides a chemically meaningful decomposition of the interaction energy between two or more fragments computed at the domain-based local pair natural orbitals coupled cluster (DLPNO-CCSD(T)) level of theory. In this work, this scheme is used in conjunction with other interpretation tools to study a series of molecular adducts held together by intermolecular interactions of different natures. The HF and corre...
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understanding the role of Dispersion in frustrated lewis pairs and classical lewis adducts a domain based local pair natural orbital coupled cluster study
Chemistry: A European Journal, 2017Co-Authors: Giovanni Bistoni, Alexander A Auer, Frank NeeseAbstract:The interaction of Lewis acids and bases in both classical Lewis adducts and frustrated Lewis pairs (FLPs) is investigated to elucidate the role that London Dispersion plays in different situations. The analysis comprises 14 different adducts between tris(pentafluorophenyl)borane and a series of phosphines, carbenes, and amines with various substituents, differing in both steric and electronic properties. The domain-based local pair natural orbital coupled-cluster (DLPNO-CCSD(T)) method is used in conjunction with the recently introduced local energy decomposition (LED) analysis to obtain state-of-the-art dissociation energies and, at the same time, a clear-cut definition of the London Dispersion Component of the interaction, with the ultimate goal of aiding in the development of designing principles for acid/base pairs with well-defined bonding features and reactivity. In agreement with previous DFT investigations, it is found that the London Dispersion dominates the interaction energy in FLPs, and is also remarkably strong in Lewis adducts. In these latter systems, its magnitude can be easily modulated by modifying the polarizability of the substituents on the basic center, which is consistent with the recently introduced concept of Dispersion energy donors. By counteracting the destabilizing energy contribution associated with the deformation of the monomers, the London Dispersion drives the stability of many Lewis adducts.
Yu Reznikov - One of the best experts on this subject based on the ideXlab platform.
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magnetic field control of the ordering of two Component suspension of hard rods
Philosophical Transactions of the Royal Society A, 2013Co-Authors: Kostyantyn Slyusarenko, Victor Yu Reshetnyak, Yu ReznikovAbstract:The Onsager theory of hard rod Dispersion in a neutral solvent is extended to a case of two-Component Dispersion consisting of both non-magnetic and magnetic rods. It was found that the alignment of magneto-sensitive Dispersion Component by a magnetic field leads to the alignment of non-magnetic Component in the Dispersion and to an elimination of the isotropic phase. This effect is significant even at low relative concentrations of magnetic rods and leads to a magnetically induced anisotropy in a non-magnetic Dispersion of rods mixed with the magnetic ones.
Anahi Calduprimo - One of the best experts on this subject based on the ideXlab platform.
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spatially extended and high velocity Dispersion molecular Component in spiral galaxies single dish versus interferometric observations
The Astronomical Journal, 2015Co-Authors: Anahi Calduprimo, Andreas Schruba, Fabian Walter, Adam K Leroy, Alberto D Bolatto, Stuart N VogelAbstract:Recent studies of the molecular medium in nearby galaxies have provided mounting evidence that the molecular gas can exist in two phases: one that is clumpy and organized as molecular clouds and another one that is more diffuse. This last Component has a higher velocity Dispersion than the clumpy one. In order to investigate these two molecular Components further, we compare the fluxes and line widths of CO in NGC 4736 and NGC 5055, two nearby spiral galaxies for which high-quality interferometric as well as single-dish data sets are available. Our analysis leads to two main results: (1) employing three different methods, we determine the flux recovery of the interferometer as compared to the single-dish to be within a range of 35%–74% for NGC 4736 and 81%–92% for NGC 5055, and (2) when focusing on high (S/N ≥ 5) lines of sight (LOSs), the single-dish line widths are larger by ∼(40 ± 20)% than the ones derived from interferometric data, which is in agreement with stacking all LOSs. These results point to a molecular gas Component that is distributed over spatial scales larger than 30″(∼1 kpc), and is therefore filtered out by the interferometer. The available observations do not allowmore » us to distinguish between a truly diffuse gas morphology and a uniform distribution of small clouds that are separated by less than the synthesized beam size (∼3″ or ∼100 pc), as they would both be invisible for the interferometer. This high velocity Dispersion Component has a Dispersion similar to what is found in the atomic medium, as traced through observations of the H i line.« less
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spatially extended and high velocity Dispersion molecular Component in spiral galaxies single dish vs interferometric observations
arXiv: Astrophysics of Galaxies, 2015Co-Authors: Anahi Calduprimo, Andreas Schruba, Fabian Walter, Adam K Leroy, Alberto D Bolatto, Stuart N VogelAbstract:Recent studies of the molecular medium in nearby galaxies have provided mounting evidence that the molecular gas can exist in two phases: one that is clumpy and organized as molecular clouds and another one that is more diffuse. This last Component has a higher velocity Dispersion than the clumpy one. In order to investigate these two molecular Components further, we compare the fluxes and line widths of CO in NGC 4736 and NGC 5055, two nearby spiral galaxies for which high-quality interferometric as well as single-dish data sets are available. Our analysis leads to two main results: 1) Employing three different methods, we determine the flux recovery of the interferometer as compared to the single-dish to be within a range of 35-74% for NGC4736 and 81-92% for NGC5055, and 2) when focusing on high (SNR>5) lines of sight, the single-dish line widths are larger by ~(40+-20)% than the ones derived from interferometric data; which is in agreement with stacking all lines of sight. These results point to a molecular gas Component that is distributed over spatial scales larger than 30"(~1kpc), and is therefore filtered out by the interferometer. The available observations do not allow us to distinguish between a truly diffuse gas morphology and a uniform distribution of small clouds that are separated by less than the synthesized beam size (~3" or ~100pc), as they would both be invisible for the interferometer. This high velocity Dispersion Component has a Dispersion similar to what is found in the atomic medium, as traced through observations of the HI line.